| Popis: |
Two novel covalently linked chromophore-quencher ruthenium(II) complexes, Ru(bpy) 2 (pyNCHAn) 2+ 2 ( 2 ; bpy=2,2′- bipyridine; pyNCHAn=4-[9-anthryl)methyl]imino-pyridine) and Ru(bpy) 2 (pyNHCH 2 An) 2+ 2 ( 3 ; pyNHCH 2 An =4-[(9-anthryl)methyl]amino-pyridine) along with the “reference’ complex Ru(bpy) 2 (pyNH 2 ) 2+ 2 ( 1 ; pyNH 2 =4- amino-pyridine), have been studied. Excitation into the Ru→bpy charge-transfer manifold is followed in 2 and 3 by fast intramolecular energy transfer to the lowest triplet excited state of an anthryl group. For 2 , the luminescence quantum yield is quenched more effectively than the luminescence lifetime. Such a behavior is accounted for when one considers the possibility of 2 to exist in a number of conformers. The nature of the connectors plays a key role in determining the extent of the intramolecular process: actually, only a partial quenching occurs in the semi-rigid molecule 2 , while the quenching is complete in 3 . |
